Apparatus for and method of heat treating ceramic materials



May 2, 1933. J. HARRINGTON 1,906,465

APPARATUS FOR AND METHOD OF HEAT TREATING CERAMIC MATERIAL Filed April 22, 1929 4 Sheets-Sheet 1 lgszpu Harm/m; TON

May 2, 1933. J. HARRINGTON 1,906,465

' APPARATUS FOR AND METHOD OF HEAT TREATING" CERAMIC MATERIAL File April 22 1929' 4 Sheets-Sheet 2 JosEpH Hfl/PlP/NG Tow y 1933- J. HARRINGTON 1,306,455

APPARATUS FOR AND METHOD OF HEAT TREATING CERAMIC MATERIAL Filed April 22, 1929 4 Sheets-Sheet 3 3 RMfi/m- JbsspH HHFPPINGTON May 2, 1933. J. HARRINGTON APPARATUS FOR AND METHOD OF HEAT TREATING CERAMIC MATERIAL Filed April 22, 1929 4 Sheets-Sheet 4 @ZW W W's Patented May 2 1933 ilhliTEE STATES means Parent cri ics JGSEPII HABRZZ'GTOIT, CF RIVERSIDE, ILLINOIS,

ASSIGNOR T0 JOSEPH HARRINGTON COMPANY, OF HARVEY, ILL N'GIS, A GOEPORATIGN OF ILLINOIS Application filed April 22,

My invention relates generally to apparatus for and methods of heat treating ceramic materials and particularly to kilns and methods of heat treating ware within kilns.

' It has heretofore been a common practice to employ kilns in which fire boxes with grates have been arranged in spaced relation along the lower section of the kiln wall. In employing such types of kilns numerous disadvantages are presented. These kilns employ natural draft and the gases from the the bones or pockets pass upwardly inside the dome of the kiln and then pass clownwardly through the perforate floor to an underground flue. Under these natural draft conditions tne hot ases will naturally pass downwardly along the path of least resistance and this frequently causes a laning of the gases from some point within the kiln toward another point of exit. That is to say, instead of the hot gases being uniformly diffused within the kiln, they are drawn downwardly through localized areas. During the water-smoking period, that is, the period when the ware is initially subjectedto heat, the only vehicle for conveying Water away from the were is the small quantity of hot as which is generated in the above mentioned fire boxes and therefore considerable time must be expended in drying the ware. During this water-smoking period the relativ ry small quantity of hot gases rise from the tire boxes to the top of the kiln. It will be understood that the ware, when initially .3 placed within the kiln, is cold and damp and that hot ases from the fire pockets serve to drive of? a certain amount of moisture from the top layers of the ware. The gas soon becomes saturated and as it descends within the kiln and is carried into contact with the lower moistened ware, condensation must neces sarily take place. In other words, an air vehicle in sulticient quantity is not provided for carrying away the moisture from the were and hence a reciepositing of the moisture takes place. Obviously, under such conditions the ware must be subjected to the hot gases for a relatively long period in order that all of the moisture might be removed.

In general, one of the primary objects of 1929. Serial no. 357,099.

my present invention is to provide a simple and durably constructed apparatus by means of which methods of heat treating ceramic materials may be efiiciently practiced to the end that the above mentioned and other disadvantages and inconveniences may be avoided. V

More specifically, it is an object of present 7 invention to provide means and methods whereby heated gases may be effectively tempered and then uniformly diifused within a heattreating chamber.

Another object of my invention is to properly and positively control the introduction of excess air into the heat treating chamb@1,Wl1lCll air will serve eiiiciently for vehicle purposes.

Another important object of my present invention is to provide methods and means whereby her or kiln may be subjected to pressure above atmospheric pressure so as to positively insure uniform diffusion of heat to all parts of the kiln chamber.

Still another and more specific object of my invention is to introduce excess air for vehicle purposes which has preliminarily been conditioned,and I contemplate introducing said conditioned air into an enclosure containing the ware in such a manner as to insure in creased efficiency in the burning of the ware.

Still another object of my invention is to eliminate the smoke nuisance which has heretofore been experienced in connection with burning the ware and to this end I propose to employ in combination with an improved kiln construction, an automatic stoker of im proved practical design.

These and numerous other objects and advantages will be more apparent from the following detailed description when considered in connection with the accompanying drawings, wherein:

Figure 1 is a vertical transverse sectional View of a kiln which is representative of one embodiment of my invention and bymeans of which my improved method of heat treating ceramic materials may be eifectively practiced, said section being taken substantially along the line 11 of Figure 2;

the interior of a heat treating cham- Cal Figure 2 is a plan view of the kiln construction shown in Figure 1;

Figure 3 is an enlarged horizontal sectional view taken substantially along the line 33 of Figure 1, which illustrates in plan the manner in which the stoker is enclosed in an air-tight compartment so as to maintain the air pressure outside of the stoker slightly greater than the pressure within the stoker;

Figure at is a diagrammatic plan view disclosing the manner in which a plurality of heating devices constructed in accordance with the teachings of my invention may be coupled together so to make for increased operating efficiency; and

Figure 5 is also a diagrammatic represen tation disclosing a side view of Figure l.

Referring now more in detail to the drawings wherein like numerals have been employed to designate similar parts throughout the various figures, it will be seen that one embodiment of my invention contemplates the provision of a dome-shaped kiln which I have indicated generally by the numeral 10. This kiln may be constructed of any suitable heat resisting material of the type which has heretofore been employed in kiln constructions. A burning or heat treating chamber 12 is enclosed by the semispherical wall 1 1 of the kiln and the floor 16 of said kiln is provided with a plurality of openings or vents 18 which communicate at their lower extremities with a common discharge conduit or passageway 20. It is to be noted that the inner surface of the kiln wall 14 is free from any projections or obstruct-ions and therefore I am able to pile ware within the kiln, which in the particular instance constitutes brick 22, so that said ware is positioned in close proximity to the inner surface of said wall. In conventional types of dome-shaped kilns fire boxes are spaced along the inner surface of the kiln wall adjacent the floor and obviously considerable space is taken up by these fire boxes or pockets. My present invention eliminates the necessity of providing these fire boxes and hence provides additional space for accommodating the ware. The upper central portion of the kiln wall 14 is provided with an opening 2 1 which communicates with a flue 0r intake passageway 26.

This flue or passageway 26 communicates at its lower extremity with the combustion chamber 28 of an automatic stoker 30 later to be described. Disposed along the conduit 26 are a plurality of pipes 32 which are all connected to a common pipe or conduit 34:. This conduit34 is connected with the discharge side of a suitable air supplying mechanism or pump 36 and it will thus be apparent that air supplied by said mechanism will be directed through the agency of the pipes 32 and 34, into the passageway 'or flue 26. To control the amount of excess air introduced within the flue 26 I provide each of the pipes 32 with suitable dampers or valves 38 which may be controlled from any convenient point as for example by means of chains 40, Figure 1. A chain or belt 42 is associated with the shaft of each damper 38. Each of these belts 12 is connected with a companion shaft 14, which shaft is in turn connected with its companion chain 10. Thus, the position of the dampers 38 may be independently actuated by merely moving the corresponding chain 40. The means for controlling the position of the dampers 38' which has just been described is merely illustrative of one system which may be employed for controlling the introduction of excess air within the flue and obviously my invention is not limited to the specific described apparatus but contemplates any practical means for efficiently controlling the introduction of excess air into the flue.

Reference has heretofore been made to the automatic stoker which is designated generally by the numeral 30 and in this connection it might be stated that my present invention does not relate to the stoker per se, as this stoker mechanism is described and claimed in my copending application, Serial No. 340,924E, filed February 18, 1929. A. more comprehensive and detailed description of the stoker proper may be had by referring to my aforementioned copending application. This stoker 30 comprises a suitable fuel hopper &6 which is adapted to direct fuel downwardly onto a horizontally reciprocable grate section 48. Fuel which is deposited upon this reciprocable grate section 48 is uniformly advanced through the combustion chamber 28 through the inter-action of other grate sections 52 and 54 which cooperate with the grate section 48. In order to maintain the air pressure surrounding the stoker 30 at a slightly greater pressure than the pressure within the stoker 1 surround said mechanism by a suitable sealing wall 56. A chamber 58 which is enclosed by the sealing wall 56, is supplied with air through the agency of a suitable motor driven pump 60. The air pressure within the chamber 58 is maintained at a slightly greater pressure than the pressure within the stoker and hence proper draft conditions upwardly through. the fuel bed supported by the stoker grates is constantly maintained. The advantages resulting from the provision of the sealing wall 56 will be apparent when it is understood that it is very difficult to construct a furnace or stoker which is free from leaks at all points. Even the porous structure of the materials used in the construction of the furnace might be sufficient to establish a certain amount of leakage. Hence, by subjecting the entire stoker unit to an increased external pressure. leakage through the stoker walls is positively prevented.

In practicing my improved method by means of the above described apparatus, the ware or brick 22 is first piled or stacked within the kiln chamber 12, space being provided between the stacked ware so as to permit the hot gases to permeate the entire stack. This ware is also arranged so as to permit the floor openings 18 to supply means of communication between the chamber 12 and the discharge passageway 20. After the Ware has been properly positioned within the kiln, the wall of said kiln is closed and heat from the stoker is directed into the flue 26. The initial heat treatment to which the ware is subjected is commonly known as the watersmoking period. During this period the moisture in the Ware or brick is driven off and in driving off the moisture by the introduction of heated gases, care must be exercised so as not to heat the ware too suddenly because the application of intense heat might result in causing the ware to crack. As the heated gases rise within the flue 26, said gases are diluted by the introduction of cool air which is supplied from the fan 36. During this water-smoking period I prefer to control the dampers 38 so as to effect the introduction within the flue 26 of a considerable volume of excess air which dilutes and tempers the hot gases issuing from the combustion chamber 28. In order to readily ascertain the exact temperature of the heated air and gases which pass through the kiln opening 24, I make use of a conventional pyrometer which I have designated generally by the numeral 62, Figures 1 and 2. This pyrometer may be connected to a suitable recording or indicating instrument 64 positioned so that it may be conveniently observed by an attendant. By observing the temper ature indicated, the attendant may control the introduction of cool air into the flue 26 and may also increase or decrease the rate of combustion within the stoker. In other WOIClS, my invention contemplates the accurate and positive control of the temperature at the point where the hot gases are introduced within the kiln chamber. The introduction of the excess volume of air not only causes a dilution of the hot gases but also causes a decrease in the resultant temperature and by proper adjustment of the above mentioned parts a relatively large volume of air at the proper temperature may be introduced within the kiln chamber during the water-smoking period. It will be apparent that if a suificient volume of air at a fairly high temperature is employed as a vehicle, the moisture taken up thereby will be quickly drawn 01f through floor openings or vents 18 and thence through the discharge passageway 20. This method of introducing excess heated air as a vehicle into the central upper portion of the kiln chamber should be clearly distinguished from the conventional methods a of water-smoking brick, tile and the like. In methods heretofore practiced the hot gases from the fire boxes or pockets spaced along the inner periphery of the kiln adjacent the floor rise within the kiln chamber and quickly take up their volume of moisture. In other words, no excess air is present to be used as a drying Vehicle. Air at a given temperature obviously will carry in suspension a certain limited weight of moisture and when this limit has been reached and the temperature is then lowered, condensation must necessarily take place. By employing my improved method of heat treating I am able to intro duce a sufiicient supply ofheated excess air to take up moisture from the ware and carry it out of the kiln chamber without any condensationa The removal of moisture from the Ware by practicing my improved method greatly reduces the duration of the watersmoking period and the heat supplied from the combustion chamber 28 is very eiiiciently employed. After the moisture has been driven off by this initial heat treating process, the temperature of the introduced gases may be raised. his can very easily be accomplished by adjusting the dampers 38 and also by varying the draft conditions within the stoker mechanism 30. The introduction of hot gases under pressure at the top of the kiln chamber and at the central portion thereof insures uniform diffusion of heat throughout the entire kiln chamber. By ins troducing the hot gases under pressure as above described, no localized areas or lanes of hot gases will be present Within the kiln chamber as is experienced in conventional types of kilns employing the natural draft principle. The attendant may conveniently manipulate the chains 40 and the rate of combustion within the stoker mechanism 30 may be controlled in order to maintain constant predetermined. temperature of the hot gases introduced within the kiln chamber. The positive control of the temperature enables the ware to be uniformly burned or heat treated and the period of heat treatment may be considerably reduced. After the ware has been subjected to the required heat treatment, the kiln wall may be opened and said Ware removed. A new supply of ware may be stacked within the kiln and subjected to heat treatment in the manner described. Thus batches of ware such as brick, tile and the like may be periodically burned in a very efiicient and practical manner. 7

Attention is directed to the fact that the apparatus just described presents a system in which the heated gases are continuously subjected toa pressure above atmospheric pressure. In other words, the air vehicle and hot gases introduced within the kiln chamber are always at a pressure above atmospheric pressure. Introducing hot gases Within a heating chamber or kiln under pressure, positively insures uniform diffusion of said gases throughout the extent of the kiln. That is to say, when the hot gases are forced into the kiln, they will instantly stratify so that the lighter gases will always be at the top and the density will increase as lower levels are approached. This stratification will be absolutely uniform and hence all the corners of the kiln will be reached and the possibilityof any laning of the gases will be precluded. This laning effect which has heretofore been experienced in using conventional types of natural draft kilns results from the presence of negative pressures Within the kiln chamber, that is, pressures below atmospheric pressure. The existence of negative pressures will naturally cause a surge of hot gases toward the negative zone and hence make for non-uniform diffusion of the gases within the kiln. lVIy invention enables the avoidance of such deleterious effects.

In Figures 4t and 5 I have diagrammatically disclosed the manner in which two or more heating devices of the type described may be coupled together. For purposes of illus tration I have designated a pair of coupled kilns generally by the letters A and B. Thus, as indicated by the directional arrows, hot gases from the combustion chamber 28 of the kiln unit A will pass through the flue 26 and downwardly within the kiln chamber 12. From the bottom of the kiln chamber 12 the gases are directed through the discharge passageway in the manner already de scribed. The opposite extremity of this passageway 20 communicates with a passageway 26a which will direct the hot gases into the upper end of the kiln chamber 12 at the left of Figures 1 and 5. The heated gases then pass downwardly through the chamber 12 and are drawn oii at the bottom through the discharge passageway 20 of the kiln unit B. In order to properly direct the flow of gases I provide suitable valves or dampers G l adjacent the upper portion of the kiln chambers 12 at the point where the passageways 26 and 26a meet and dampers 66 adjacent the lower portion of the kiln chambers. When these dampers 64 and 66 occupy the solid line positions shown in Figure 5. the gases from the combustion chamber of the unit A will follow the path just described and in this way the heat employed in the unit A-may also be utilized for treating the ware within the kiln unit B. Obviously, additional units might be coupled together without departing from the spirit and scope of my invention. By actuating the dampers 64F. and 66. the flow of hot gases might be reversed. That is to say, the heat supplied from the combustion chamber of the kiln unit B might be directed into association with the ware of the unit A. Also each unit may be operated independently of the other by merely adjusting the positions of the dampers. By employing the above described coupled arrangement, the hot gases from one kiln may be introduced under pressure within the adjacent kiln and thereby a marked saving in fuel is obtained. In other words, the exit hot gases from one kiln may be used for water-smoking or preliminarily heating the ware in the adjacent kiln.

The, apparatus just described and the method capable of being practiced by the use thereof present numerous advantages over other types of apparatus and methods which have been brought to my knowledge. Some of these distinct advantages may be summarized as follows: The ware is subjected to uniform heat conditions and hence a uniformly burned or heat treated product results; the capacity of the kiln is greatly increased by reason of the fact that no bag walls or pockets are provided therein; the introduction of air into the flue serves to temper the hot gases in a very efficient manner and provides a vehicle for drying purposes; the introduction of tempered hot gases under pressure at the upper central portion of the kiln chamber makesfor uniform and complete diffusion of the hot gases within the kiln chamber; the laning or localizing of heated gas areas is positively prevented; the provision of a flue having appreciable length insures complete combustion, and provides a convenient place for the introduction of vehicle air; by employing a stoker mechanism of the type described in combination with the kiln, the smoke nuisance which has heretofore been experienced, will be abated because complete combustion is effected; and the described apparatus is of simple and practical construction.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

In heat treating apparatus of the class described, a chamber for receiving a supply of ware to be treated, means for supplying heated gases, a flue for conducting said heated gases into said chamber, and means for introducing a supercharge of air within the iiue for association with said heated gases.

2. in apparatus of the class described for heat treating ceramic materials and the like, a chamber for receiving a supply of ware to be heat treated, means for supplying heated gases, means for conducting said heated gases into the upper central portion of said chamber, and means for controlling the temperature of the heated gases supplied to said oh amber.

3. In heating apparatus of the class described, a kiln having a chamber for receiving a supply of ware, means for supplying heated gases. an elongated flue connecting said gas supplying means wit-h the kiln chamher, and means for directing a supercharge of air into said flue for association with said heated gases.

4-. In combination with a chamber of a kila furnace for supplying heated gases, a flue connecting the top of the kiln'with said furnace, and means for supplying air to sair flue.

5. In combination with the chamber of a kiln a furnace for en Jl i119 heated ases a flue connecting said furnace with the upper portion of the kiln chamber, means for supplying air to said flue, a casing enclosing said furnace,and means for supplying air within i said enclosure to maintain a pressure surrounding the furnace greater than the pressure within the furnace.

6. In heat treating apparatus of the class described, a dome-shaped kiln having a chamber for receiving ware to be treated, a furnace for supplying heated gases, a flue connecting said furnace with the upper central portion of said dome-shaped kiln, and means for controlling the temperature of the gases directed into said kiln.

7. In apparatus of the class described for heat treating ceramic materials and the like, a dome-shaped kiln having chamber for receiving ware to be treated, a furnace for supplying heated gases. a flue connecting said furnace with the upper central portion of said dome-shaped kiln, and means for supplying air under pressure to said flue for association with the heated gases therein.

' whereby said heated gases will be effectively tempered and a vehicle for carrying off the moisture is provided.

8. In apparatus of the class described for heat treating ceramic materials and the like, kiln chamber for receiving wars to be treated, an external furnace for generating heat. and means for conducting heated gases from said furnace into the upper central portion of the kiln chamber at a pressure above atmospheric pressure.

9. In apparatus of the class described for heat treating ceramic materials and the like. a heat treating kiln chamber. means for supplying heated gases at a pressure above atmospheric pressure, and means for introducing said heated gases into the upper portion of said ki n chamber.

10. In heat treating apparatus of the class described, a kiln chamber for receiving a supply of ware to be heat treated, an external furnace for supplying heated gases under pressure in excess of atmospheric pressure, and means for conducting said heated gases into said kiln chamber, whereby the pressure of the gases in said kiln chamber will be maintained above atmospheric pressure.

11. The method of heat treating ceramic materials which consists in placing the material within a chamber, introducing a supply of heated gases under pressure at the top of said chamber, uniformly diffusing said gases throughout the entire chamber and withdrawing said gases at the lower portion of said chamber,

12. The method of heat treating ceramic materials which consists in placing the material within a chamber, and treating said material with heated gases supercharged with air at a pressure above atmospheric pressure so as to obtain uniform diffusion of the gases within said chamber.

13. The method of heat treating ceramic materials which consists in placing material within a chamber, treating said material with heated gases at a pressure above atmospheric .ressure so as to obtain uniform diffusion of the gases within said chamber, withdrawing heated gases from said chamber, and then employing said withdrawn gases for treating another quantity of ceramic material.

14. The method of heat treating ceramic materials which consists in placing material within a chamber, introducing a supply of heated gases at the top of said chamber, uniformly diffusing said gases throughout the entire chamber, withdrawing said gases at the lower portion of said chamber, and utilizing said withdrawn gases for'heat treating another supply of ceramic material.

15. The method of heat treating ceramic materials which consists in placing the material within a chamber, introducing a supply of heated gases at the top of said chamber, uniformly diffusing said. gases throughout the entire chamber, withdrawing said gases at the lower portion of said chamber, and then directing said withdrawn gases into the top of a second chamber containing a supply of ceramic materials.

16. In heat treating apparatus of the class described for heat treating ceramic materials and the like, a kiln chamber for receiving asupply of ware to be heat treated, a unitary external furnace providing the sole supply for heated gases, and means for directing heated gases from said unitary external source of supply into the upper portion of said chamber.

17. In an apparatus of the class described for heat treating ceramic materials and the like, a heat treating chamber for receiving ware to be treated, a unitary furnace for supplying all of the heated gases necessary for treating the ware, means for directing the heated gases from said furnace into the upper portion of the chamber, and means for directing a supply of air into association with said heated gases.

18. In apparatus of the class described for heat treating ceramic materials and the like, a heat treating chamber for receiving ware to be treated, an automatic stoker for supplying heated gases, and means for directing id's iio

. being greater than the pressure within the ed gases, and a flue connecting said automatic stoker with the upper portion of the kiln 5; said furnace andin an amount which is in chamber, whereby gases from said automatic stoker may be employed for heat treating the ware within the kiln.

20. In combination with the chamber of a kiln, a furnace for supplying heated gases, a flue connecting said furnace with said kiln, and means for directing air into association with said heated gases at a point spaced from excess of the amount of air required for combustion purposes within the furnace.

21. Incombination with a chamber of a kiln, afurnace for supplying heated gases to said chamber, a flue connecting said furnace with said kiln, and means for directing air into association with said heated gases in an amount which is in excess of the amount required for combustion purposes within the furnace. a

22. In combination with the chamber of a kiln, a furnace for supplying heated gases to said chamber, a flue connecting said furnace with the kiln chamber, acasing enclosing said furnace, and means for supplying air within said enclosure to maintain a pressure surrounding the furnace greater than the pressure within thejfurnace,

23. In combination with the chamber of a kiln, a furnace for supplying heated gases, a flue connecting said furnace with the kiln chamber, means for supplying excess air for the heated gases, and a casing enclosing said furnace, the pressure within said enclosure furnace.

24. In combination with the chamber of a kiln, an external furnace, said furnace being adapted to effect the complete and smokeless combustion of bituminous fuel, and means for conducting smokeless, heated gases from said furnace into the kiln chamber for treating the ware within said chamber.

25. In combination with the chamber of a kiln, an external furnace, said furnace being adapted to effect the complete and smokeless combustion of bituminous fuel, means for conducting smokeless, heated gases from said furnace into the kiln chamber for treating the ware within said chamber, and means for introducing air into association with the heated gases, which air is in excess of that required to complete combustion of the bituminous fuel within the confines of the furnace.

26. The method of heat treating ware within the chamber of a kiln, which consists in burning bituminous fuel in an external combustion chamber with the correct amount of air for complete and smokeless combustion within the confines of said chamber, tempering the hot gases given off from the combustion chamber to a degree required by the ware within the kiln, and then subjecting said ware to the tempered, heated gases.

27. The method of heat treating ware within the chamber of a kiln, which consists in burning bituminous fuel in an external furnace with the correct amount of air for complete smokeless combustion within the confines of said external furnace, so as to supply heated gases, di'luting said heated gases with an excess supply of air to a degree required by the ware within the kiln chamber, and then subjecting said ware to said diluted, heated gases.

In witness whereof, I have hereunto subscribed my name.

JOSEPH HARRINGTON. 

